Drug treatments in Alzheimer's
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Introduction
This leaflet is about the drugs used to treat Alzheimer's
disease. It discusses how the drugs work, why they are prescribed,
their side-effects and alternative treatments. Alzheimer's disease
is only one of many possible causes for memory problems in people.
The other causes are described in detail in our leaflet on memory problems and dementia.
Cholinesterase Inhibitors
What are Cholinesterase
inhibitors?These are the main drugs used for Alzheimer's
disease in the UK. Three drugs are currently licensed:
| Drug name |
Other name |
| Donepezil |
Aricept® |
| Galantamine |
Reminyl® |
| Rivastigmine |
Exelon® |
There are no major differences between these drugs. They are
all designed to help the symptoms of Alzheimer's disease
- for example, memory loss and anxiety. They are not a cure, though
they may slow the course of the illness.
What effect can these drugs have?
They can improve memory. They can also have general benefits
including improving alertness and motivation. It may take some
months for there to be a noticeable improvement or slowing down of
memory loss. Some people feel brighter in their mood and
will be able to do things that were too hard for them, such as
going shopping.
What side-effects are there?
The most common side-effects are feeling sick, loss of
appetite, tiredness, diarrhoea, muscle cramps and sometimes poor
sleep. These may be reduced or avoided by increasing the dose
slowly, or taking the medicine after food. The side-effects usually
fade after a few weeks and will go away if the medicine is stopped.
More information about side-effects can be obtained from your
doctor or by reading the leaflet that comes with the
tablets.
How do they work?
Acetylcholine is a chemical that helps pass messages between
certain brain cells involved in memory. In Alzheimer's disease,
these brain cells start to die and the amount of acetylcholine is
very much reduced. Memory starts to suffer. Cholinesterase
Inhibitors reduce the breakdown of acetylcholine and increases its
levels in the brain. This reduces some of the symptoms of
Alzheimer's disease.
How well do they work?
About 50-60% of people on these drugs show a slight
improvement or a stabilisation of their condition over 6
months. Unfortunately, not everyone benefits from these drugs,
and if no improvement or stabilisation is seen in the first few
months, then they should be stopped.
How should these drugs be taken?
It is usual to start on a low dose which is gradually
increased. Don't be put off by any side-effects early on in the
treatment as these usually wear off after a few weeks. It is
important to take the drugs every day for them to be
effective.
How long should these drugs be taken?
These drugs are usually prescribed for a trial period
of 3 to 4 months to see if they show signs of helping. There
is no clear view as to how long they should be taken. If the
condition progresses in spite of treatment, there may come a point
when you and your doctor decide that there is little point in
staying on them.
Who can prescribe these drugs?
A specialist, rather than your GP, will prescribe
the medicine during this trial period. You will usually
see the specialist in a hospital clinic. You may need blood tests
and a brain scan to exclude any other causes for the memory loss.
In some areas, the specialist will continue to prescribe the drug
if they conclude that it is working. In other areas, the GP will
prescribe it after the trial period.
Memantine
This drug is also known as Ebixa. It is thought to work by
affecting a chemical in the brain called glutamate. In Alzheimer's
disease, too much glutamate leaks out of damaged brain cells and
interferes with learning and memory. In some studies, about half
the people taking Memantine show some slowing down of the dementia
in the later stages. The main side-effects of Memantine - which are
usualy mild - are nausea, restlessness, stomach ache and headache.
This drug is used in moderate dementia if the cholinesterase
inhibitors cause undue side-effects. It may also help in the more
severe stages of the illness.
Other Treatments
Ginkgo biloba
This is a naturally occurring substance extracted from the
Maidenhair tree. It has long been thought to enhance memory.
However, a recent study looked at the effects in Ginkgo in
over 3000 people taking it for an average of 6 years.
Unfortunately, Gingko did not stop dementia developing and, in a
small number of people with heart problems, it actually seemed to
make their dementia worse.
Vitamin E
This is a natural substance found in oils from
soya beans, sunflower seeds, corn and cotton seed, as well as
whole-grain foods, fish-liver oils and nuts. Vitamin E
has many functions in the body. Vitamin E deficiencies
are very rare.
Some studies suggest that taking Vitamin E can slow the
progression of Alzheimer's disease. However, more
research needs to be done to be certain of this. It can interfere
with blood clotting and should be used with caution in people with
a clotting disorder and on blood thinning drugs, although it can be
used with aspirin.
In 2004 a review of studies involving a total of over 136,000
patients suggested doses over 400 units a day
probably do more harm than good. Some experts therefore suggest
that not more than 200 units a day should be taken.
There is some evidence that a diet rich in natural Vitamin E
may reduce the risk of developing Alzheimer's disease.
New drugs
Rember is a drug which might reduce the tau
protein that causes 'tangles' in the brain cells of people with
Alzheimer's. It is hoped this treatment may slow the progression of
the disease. Large studies are now taking place.
'Plaques' are caused by a protein called
amyloid which build up in the brains of people with Alzheimer's.
Researchers have tried immunising people against the amyloid. The
most recent trial found a reduction in the plaques. Unfortunately,
this did not lead to improvements in memory.
Dimebon is a drug that was used to treat hay
fever. Some research suggest that it may help in Alzheimer's. It is
not clear how the drug works, but it may protect nerve cells.
Etanercept blocks the chemical
TNFα which causes inflammation and cell death. This
drug is also used to treat arthritis. Researchers in California
injected the drug into the spine. They found improvements in a
small number of people with Alzheimer's disease. However, many
people have criticised the study. More research needs to be done to
see if the claims are correct.
It may be possible to try some of these newer treatments by
entering into a drug trial. Speak to your GP, a specialist or a
national organisation, such as the Alzheimer's Society, for
advice.
References :
- Memory problems and dementia. A
leaflet by the Royal College of Psychiatrists.
- Donepezil, Galantamine,
Rivastigmine (review) and Memantine for the Treatment of
Alzheimer's Disease, National Institute for Health and Clinical
Excellence (2009).
- Access to drugs:
Alzheimer's Society (2011).
- Ginkgo Biloba - JAMA 2008;300:2253-62.
- Vitamin E for Alzheimer's disease, Cochrane Review 2008
- Professor Wischik, Presentation on rember TM
at the Alzheimer's Association International Conference on
Alzheimer's Disease (ICAD 2008) in Chicago, Illinois
- Holmes et al (2008) Long-term effects of Aβ42
immunisation in Alzheimer's disease: follow-up of a randomised,
placebo-controlled phase I trial, Lancet, 372,
216-223.
- Doody et al (2008) Effect of dimebon on cognition, activities
of daily living, behaviour, and global function in patients with
mild-to-moderate Alzheimer's disease: a randomised, double-blind,
placebo controlled study, Lancet, 372, 207-215.
- Tobinick, E (2007) Perispinal Etanercept for the Treatment of
Alzheimer's disease, Current Alzheimer Research, 4, 5,
550-552(3).
Further reading
This leaflet was produced by the Royal College of
Psychiatrists' Public Education Editorial Board.
Series editor: Dr Philip Timms.
Written by: Dr Laura Hill, Specialist Registrar in Psychiatry
& Dr Martin Briscoe, Consultant Psychiatrist, Devon Partnership
Trust.
Last updated: March 2011; Review date: March 2013
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